Vitamin D Cuts Pancreatic Cancer Risk

Taking vitamin D cut the risk of pancreatic cancer nearly in half, according to a new study that is being called the first to show such a benefit.

Vitamin D protects against colorectal and breast cancer, earlier studies have found. And lab and animal studies show it stifles abnormal cell growth and curbs formation of blood vessels that feed tumors.

“I’ve been converted from a skeptic about a role of vitamin D in preventing cancer to a believer that there’s something there,” said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society.

Taking 450 international units (IUs) of vitamin D — about the standard dose in most multivitamins — reduced the risk of pancreatic cancer by 43 percent, according to researchers at Northwestern and Harvard universities who led the latest study.

There was no significant added benefit from taking more than that amount. But there was decreased benefit from taking less: Taking 150 to 300 IUs a day reduced the risk of pancreatic cancer by just 22 percent, the researchers found.

“The take-home message is that it’s important to maintain adequate vitamin D intake,” said Hal Skinner, who led the research.

The study appears in the September issue of a medical journal, Cancer Epidemiology Biomarkers & Prevention.

The research drew data from two earlier studies, one of more than 46,000 men and one of more than 75,000 women, that followed study participants for decades. In the 1980s, people in both studies were asked detailed questions about their diet. From those responses, the researchers calculated the daily intake of vitamin D, calcium, and a form of vitamin A called retinol.

The researchers then looked at who later developed pancreatic cancer, and also looked at smoking history and other factors.

Through a statistical analysis, they concluded 12.5 cases of pancreatic cancer occurred each year per 100,000 people taking 600 or more IUs of vitamin D. The rate was 21 cases for patients taking below 150 IUs each day.

The body makes vitamin D from sunlight, but the researchers were not able to assess sunlight exposure in the participants, said Skinner, who was at Northwestern at the time of the study but now is assistant professor of population health sciences at the University of Wisconsin.

Vitamin D is also found in salmon, tuna and other oily fish, and is routinely added to milk. Government advisers have suggested 400 IUs of vitamin D for people ages 50 to 70, and 600 IUs for people over 70, but lower levels for younger people.

Multivitamins often package retinol with vitamin D to promote bone health, but it appears retinol has a diluting effect on the benefits of vitamin D against pancreatic cancer, Skinner said.
More research needs to be done into whether nutritional supplements that contain vitamin D alone are better cancer fighters than those that include retinol, he suggested.

Pancreatic cancer is relatively rare, accounting for just 2 percent of new cancer cases in the United States. But it’s also highly lethal — the fourth-deadliest cancer in the United States. About 33,700 Americans will be diagnosed with pancreatic cancer this year, and 32,300 will die.

There is no early-detection test. Early symptoms are vague complaints like indigestion. More telling symptoms, like yellowing skin, usually don’t appear until the cancer has spread and patients may have only months to live.